(1) Field of the Invention
The present invention relates to a portable power source, particularly, to a portable power source using a fuel cell.
(2) Description of Related Art
Since phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC) convert chemical energy of supplied gas into electric energy, they retain superior efficiency in the generation of electricity. The fuel cells with capacity of 100 W to 100 kW are already in practical use, and particularly, the compact fuel cells are used as a power source for apparatus in outside transmissions, the civil engineering and construction, or the like.
Conventional power sources using compact fuel cells have a number of air inlets and a number of reactant gas outlets on the several surfaces of the cases enclosing the fuel cells, from which the air leaks into the cases when the power sources are not in use. Then electrolyte of the fuel cells(for instance, phosphoric acid) absorbs water in the air, deteriorating its concentration and therefore, cell characteristics. Accordingly, valves are formed at the inlets and outlets in order to shut off the air, even though satisfactory results are not obtained. In addition, forming the valves makes the construction of the power sources more complicated as well as adding weight thereto, which makes them unfavorable for portable ones.